A chance accident brings Charlotte Heywood to Sanditon, a seaside resort on the cusp of dramatic change. Spirited and unconventional, Charlotte is initially keen to experience everything the town has to offer, but is then shocked by its scheming and ambitious inhabitants and intrigued by the secrets they share.

Charlotte and Sidney clash again, only for Charlotte to be left confused by a chance encounter. Tensions surrounding Miss Lambe's arrival in Sanditon erupt at Lady Denham's grand pineapple luncheon, and Esther and Edward realise that Clara poses a significant threat to their ambitions.

Charlotte sets out to avoid Sidney, until a serious accident forces them together and to reappraise each other. When Tom brings a new doctor to the town, he and Lady Denham clash and Clara makes a bold move in her bid to outplay Sir Edward and Esther.

The arrival of Miss Lambe's forbidden love causes Charlotte to question her opinion of Sidney. Meanwhile, Clara witnesses a moment between Esther and Sir Edward that raises her suspicions about their relationship, with awful consequences for Esther.

Tensions between Tom and his labourers erupt during the Sanditon cricket match. Charlotte and Sidney continue to clash, resulting in Miss Lambe being placed in terrible danger. Lord Babington offers Esther a glimpse of a better future.

Charlotte and Sidney are at loggerheads but must work together to try and rescue Miss Lambe. Tom tries to save Sanditon and his marriage, whilst Edward and Clara enter into a scandalous pact to try and finally win Lady Denham's inheritance.